One of our major objectives involves the study of membranes of the epithelial cell of the small intestine using techniques developed in our laboratory which permit the isolation and separation of microvillus and basolateral membranes. We will examine the factors influencing the transport of nutrients, especially sugar and amino acids by membrane vesicles. We will also study the differences in uptake and translocation by the membranes from mature differentiated villus cells compared to undifferentiated crypt cells. Changes in membrane function in absorptive disorders such as gluten-induced enteropathy (sprue) will be investigated. We are also examining the role of metabolic and immunologic changes in inflammatory bowel disease. Special attention will be given to the role of immune complexes and their components in the intestinal mucosa of such patients.